Highly responsive instrument seal

ABSTRACT

A surgical access port for passage through body tissue to provide access to an underlying tissue site is provided. The access port has a working channel dimensioned for receiving a surgical instrument and a seal assembly for providing a substantial seal before, during and after insertion of a surgical instrument. The seal assembly includes an instrument seal and a zero seal. The instrument seal includes a proximal base that is interconnected to a distal instrument engaging portion by an elongate supporting portion. The engaging portion has a lateral dimension larger than the lateral dimension of the supporting portion forming a bulbous, mushroom-like head. The lateral dimension of the engaging portion decreases toward a distal opening of the instrument seal such that the distal end of the engaging portion is substantially perpendicular to the seal axis. The supporting portion closely conforms to an inserted instrument and serves to align the distal end of the seal.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation of U.S. application Ser. No.15/221,894 entitled “Highly responsive instrument seal” filed Jul. 28,2016 incorporated herein by reference in its entirety, which is acontinuation of U.S. application Ser. No. 14/931,565 entitled “Highlyresponsive instrument seal” filed Nov. 3, 2015 now U.S. Pat. No.9,427,257 issued on Aug. 30, 2016 incorporated herein by reference inits entirety, which is a continuation of International Application No.PCT/US2015/039582 entitled “Highly responsive instrument seal” filed onJul. 8, 2015 and incorporated herein by reference in its entirety whichclaims priority to and benefit of U.S. Provisional Patent ApplicationSer. No. 62/022,039 entitled “Highly responsive instrument seal” filedon Jul. 8, 2014 which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

This application relates to surgical instruments, and in particular, tosurgical access devices such as trocars comprising a seal assembly.

BACKGROUND OF THE INVENTION

Laparoscopic surgery is a type of minimally invasive surgery in whichinstruments access internal structures of a patient's body through oneor more access devices or trocars. In some laparoscopic procedures, abody cavity is inflated or insufflated with an insufflation gas, forexample, carbon dioxide, which provides additional room for manipulatingthe instruments in the body cavity, thereby facilitating the surgicalprocedure. The term “pneumoperitoneum” refers to an abdominal cavity inan insufflated state. To maintain pneumoperitoneum, trocars are equippedwith one or more seals that prevent insufflation gas from escaping asinstruments are inserted, withdrawn, and/or manipulated during anoperation. These seals typically comprise elastomeric materials and sealcircumferentially against an inserted instrument. Usually, a zero sealand an instrument seal are employed within the trocar.

Numerous technical challenges confront those designing and manufacturingseals for trocars. For example, as an instrument is moved with respectto a seal, the seal will rub against the instrument and create friction.Stiction and hysteresis will also arise. Stiction is the static frictionof a stationary instrument in contact with a stationary seal that needsto be overcome to enable their relative motion. Elastomeric sealmaterials elongate when instruments are inserted, thereby increasingdrag force. Oil canning, or the inversion or folding over, of typicalseals can also result in loss of precise instrument control and movementbecause the surgeon experiences a different feedback between large andsmall changes in the position of the instrument. These aspects,including friction, stiction, hysteresis and oil canning, must beminimized if a seal is to be used in very delicate and preciseprocedures wherein an instrument must be maneuvered accurately withoutrestriction. Examples of seal technology which overcome these problemsinclude U.S. Pat. Nos. 8,684,975, 8,613,727, 8,562,569, 5,385,553 issuedto Applied Medical Resources Corporation and incorporated by referencein their entirety herein. These patents provide floating and pendantseals that are configured to follow the motion of an inserted instrumentand allow a minimum sealing pressure upon the shaft of an instrument.The present invention provides a new and improved trocar having a sealwith significantly reduced friction, stiction, hysteresis and oilcanning properties.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a surgical access devicehaving a working channel extending along a longitudinal axis between aproximal end and a distal end is provided. The surgical access deviceincludes a seal housing and a cannula extending distally from the sealhousing. The device further includes a seal assembly disposed inmechanical cooperation with the seal housing. The seal assembly includesan instrument seal disposed in the working channel. The instrument sealhas a central lumen extending along a central seal axis between aproximal opening at a proximal end of the instrument seal and a distalopening at a distal end of the instrument seal. The proximal opening andthe distal opening are coaxial with the seal axis. The instrument sealincludes a base portion at the proximal end of the instrument sealdefining the proximal opening. The base portion extendscircumferentially outwardly from the proximal opening. The central lumenat the base portion has a first diameter. The instrument seal furtherincludes a cylindrical supporting portion extending distally from thebase portion along the seal axis. The supporting portion has a proximalend and a distal end. The supporting portion includes an inner surfaceand an outer surface defining a wall thickness therebetween. Thesupporting portion has a circular cross-section taken perpendicular tothe seal axis. The central lumen at the supporting portion has a seconddiameter that is constant along the length of the supporting portion.The instrument seal further includes an instrument engaging portionintegrally formed with and extending distally from the supportingportion. The instrument engaging portion includes an outer surface andan inner surface defining a partial spherical shape and having a maximumdiameter that is larger than the second diameter. The instrumentengaging portion defines the distal opening at the distal end of theinstrument seal formed in the spherical shape. The distal opening has adistal diameter that is smaller than the second diameter. The baseportion is connected to the seal housing such that the distal end of theinstrument seal is allowed to pendulate with respect to the sealhousing.

According to another aspect of the invention, a surgical access port forpassage through body tissue to provide access to an underlying tissuesite is provided. The surgical access port includes a working channelextending from a proximal end and a distal end. The working channel isdimensioned for receiving a surgical instrument. The access port furtherincludes a seal assembly for providing a substantial seal before, duringand after insertion of a surgical instrument. The seal assembly isdisposed in the working channel and includes a seal holder, aninstrument seal and a zero seal. The instrument seal includes a proximalbase that is interconnected to a distal instrument engaging portion byan elongate supporting portion. The engaging portion has a diameterlarger than the diameter of the supporting portion forming amushroom-like head. The diameter of the engaging portion decreasestoward a distal opening of the instrument seal such that the distal endof the engaging portion is substantially perpendicular to a seal axis.The supporting portion closely conforms to an inserted surgicalinstrument and aligns the distal opening at the distal end of theinstrument engaging portion with the inserted instrument before theinserted instrument enters the instrument engaging portion from aproximal opening of the instrument seal. The proximal opening and thedistal opening of the instrument seal are coaxial with the seal axis.

According to another aspect of the invention, a surgical seal assemblyfor use with a surgical access device having a longitudinal axis isprovided. The seal assembly includes a seal holder including a wallportion defining a working channel dimensioned to permit passage of asurgical instrument. The seal assembly includes an instrument sealconnected to the seal holder and disposed in the working channel. Theinstrument seal has a central lumen extending along a central seal axisbetween a proximal opening at the proximal end of the instrument sealand a distal orifice at a distal end of the instrument seal. Theinstrument seal includes a base portion at the proximal end of theinstrument seal. The base extends laterally outwardly from the proximalopening. The instrument seal includes an elongate throat portionextending distally from the base portion along the seal axis. The throatportion has a throat length along the seal axis between a proximal endand a distal end of the throat portion. The central lumen has a throatdiameter that is substantially constant along the length of the throatportion. The instrument seal further includes a head portion extendingdistally from the distal end of the throat portion. The head portion hasa proximal end and a distal end. The head portion defines the distalorifice of the instrument seal at the distal end of the head portion.The distal orifice and the proximal opening are coaxial with the sealaxis. The head portion has a head diameter larger than the throatdiameter. The head diameter decreases toward the distal orifice. Thedistal orifice has an orifice diameter that is smaller than the throatdiameter. The base portion is connected to the seal holder such that thethroat portion pendulates together with the head portion.

According to another aspect of the invention, a surgical seal assemblyfor use with a surgical access device having a longitudinal axis isprovided. The seal assembly includes a seal holder including a wallportion defining a working channel dimensioned to permit passage of asurgical instrument. The seal assembly further includes an instrumentseal connected to the seal holder and disposed in the working channel.The instrument seal has a central lumen extending along a central sealaxis between a proximal opening at the proximal end of the instrumentseal and a distal orifice at a distal end of the instrument seal. Theinstrument seal includes a base portion at the proximal end of theinstrument seal. The base portion extends laterally outwardly from theproximal opening. The instrument seal further includes an elongatethroat portion extending distally from the base portion along the sealaxis. The throat portion has a throat length along the seal axis betweena proximal end and a distal end of the throat portion. The central lumenhas a throat diameter that is substantially constant along the length ofthe throat portion. The throat length is substantially greater than thethroat diameter. The instrument seal further includes a head portionextending distally from the distal end of the throat portion. The headportion has a proximal end and a distal end. The head portion definesthe distal orifice of the instrument seal at the distal end of the headportion. The distal orifice and the proximal opening are coaxial withthe seal axis. The head portion has a head diameter larger than thethroat diameter. The head diameter decreases toward the distal orifice.The distal orifice has an orifice diameter that is smaller than thethroat diameter. The ratio of the throat diameter to the throat lengthis approximately 1:2.

According to another aspect of the invention, a surgical access devicehaving a working channel extending along a longitudinal axis between aproximal end and a distal end is provided. The surgical access deviceincludes a seal housing and a cannula extending distally from the sealhousing. The device further includes a seal assembly disposed inmechanical cooperation with the seal housing. The seal assembly includesan instrument seal disposed in the working channel. The instrument sealhas a central lumen extending along a central seal axis between aproximal opening at a proximal end of the instrument seal and a distalopening at a distal end of the instrument seal. The instrument sealincludes a base portion at the proximal end defining the proximalopening. The base portion extends laterally outwardly from the proximalopening. The central lumen at the base portion has a first diameter. Theinstrument seal further includes an elongate supporting portionextending distally from the base portion along the seal axis. Thesupporting portion includes an inner surface and an outer surfacedefining a thickness therebetween. The central lumen at the supportingportion defines a second diameter. The instrument seal further includesan instrument engaging portion having a proximal end and a distal end.The instrument engaging portion extends distally along the seal axisfrom the supporting portion. The instrument engaging portion defines thedistal opening at the distal end of the instrument seal. The distalopening has a distal diameter that is smaller than the second diameter.The instrument engaging portion includes an outer surface and an innersurface defining a curved shape having a third diameter that increasesfrom the second diameter at the proximal end and decreases progressivelyto the distal diameter. The base portion is fixed to the seal housingsuch that the supporting portion and instrument engaging portion of theinstrument seal are allowed to pendulate relative to the seal housing.

According to another aspect of the invention, a surgical access devicehaving a working channel extending along a longitudinal axis between aproximal end and a distal end dimensioned and adapted for receiving asurgical instrument is provided. The surgical access device includes aseal housing and a cannula extending distally from the seal housing. Thesurgical access device further includes a seal assembly disposed in theseal housing. The seal assembly is configured to form a seal around aninstrument inserted into the working channel at the proximal end andextending through the working channel at the distal end. The sealassembly includes an instrument seal disposed in the working channel.The instrument seal has a central lumen extending along a central sealaxis between a proximal opening at a proximal end and a distal openingat a distal end of the instrument seal. The instrument seal includesfurther includes a base portion defining the proximal opening of thecentral lumen. The base portion extends laterally outwardly at theproximal opening and has an upper surface and a lower surface defining athickness therebetween. The instrument seal further includes acylindrical supporting portion extending distally from the base portion.The cylindrical supporting portion includes an inner surface and anouter surface defining a thickness therebetween. The central lumen has asubstantially constant diameter along the central seal axis from aproximal end of the supporting portion to a distal end of the supportingportion. The instrument seal further includes an instrument engagingportion having a proximal end and a distal end. The instrument engagingportion extends distally from the supporting portion. The distal openingof the instrument seal is formed at the distal end of the instrumentengaging portion. The distal opening is dimensioned and adapted to sealagainst an instrument inserted into the instrument seal. The instrumentengaging portion has a bulbous shape and has a diameter larger than thediameter of the supporting portion. The instrument engaging portion iscurved such that the instrument engaging portion at the distal openingis substantially perpendicular to the central seal axis when in arelaxed undeflected configuration.

According to one aspect of the invention, an instrument seal for use ina surgical access device is provided. The instrument seal includes aninstrument engaging portion connected to an elongate support portionthat is, in turn, connected to a resilient and responsive base portion.

According to another aspect of the invention, an instrument seal for usein a surgical access device is provided. The instrument seal includes asemi-spherical instrument engaging portion having an orifice sized andconfigured to provide a gas-tight seal against an inserted instrument.The proximal end of the instrument seal is connected to a rigid orsemi-rigid elongate support portion which at its proximal end isconnected to a highly resilient base portion; the base portion beingmore resilient/flexible than the elongate support portion. The surgicalaccess device may further be provided with a zero seal having a distalopening that is distal to the orifice of the instrument seal.

According to another aspect of the invention, an instrument seal for usein a surgical access device is provided. The instrument seal includes asemi-spherical instrument engaging portion having an orifice sized andconfigured to provide a gas-tight seal against an inserted instrument.The proximal end of the instrument seal is connected to a rigid orsemi-rigid elongate support portion that is relatively lessflexible/resilient than the instrument engaging portion. The supportportion has an appropriate length-to-diameter ratio. The proximal end ofsupport portion is connected to a highly-resilient and/or convolutedbase portion. The base portion is more flexible/resilient compared tothe support portion and/or has one or more convolutions to providegreater flexibility, resiliency and responsiveness to the instrumentseal. The surgical access device may be further provided with a zeroseal having a distal opening that is distal to the orifice of theinstrument seal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a surgical access device accordingto the present invention.

FIG. 2 is a cross-sectional view of a surgical access device accordingto the present invention.

FIG. 3 is a cross-sectional view of a seal assembly and housingaccording to the present invention.

FIG. 4A is a cross-sectional view of an instrument seal according to thepresent invention.

FIG. 4B is a cross-sectional view of an instrument seal and housing capaccording to the present invention.

FIG. 5 is a cross-sectional view of an instrument seal according to thepresent invention.

FIG. 6 is a cross-sectional view of an instrument seal according to thepresent invention.

FIG. 7 is a cross-sectional view of an instrument seal according to thepresent invention.

FIG. 8 is a bottom perspective view of an instrument seal according tothe present invention.

FIG. 9 is a bottom perspective view of an instrument seal according tothe present invention.

FIG. 10 is a cross-sectional view of an instrument seal according to thepresent invention.

FIG. 11 is a partially transparent view of an instrument inserted into asurgical access system according to the present invention.

FIG. 12 is a partially transparent view of an instrument inserted into asurgical access system according to the present invention.

FIG. 13 is a side view of an instrument inserted through a cap andinstrument seal according to the present invention.

FIG. 14 is a bottom perspective view of an instrument inserted through acap and an instrument seal according to the present invention.

FIG. 15 is a side sectional view of an instrument inserted into a capand a traditional instrument seal.

FIG. 16 is a side sectional view of an instrument inserted into a capillustrating a traditional instrument seal superimposed with aninstrument seal according to the present invention.

FIG. 17 is a bottom perspective, cross-sectional view of an instrumentinserted into a cap with a traditional seal superimposed on aninstrument seal according to the present invention.

FIG. 18A is a cross-sectional view of an instrument inserted through aninstrument seal according to the present invention.

FIG. 18B is a cross-sectional view of an instrument inserted through aninstrument seal according to the present invention.

FIG. 19A is a cross-sectional view of an instrument inserted through aninstrument seal according to the present invention.

FIG. 19B is a cross-sectional view of an instrument inserted through aninstrument seal according to the present invention.

FIG. 20A is a sectional view of an instrument inserted into aninstrument seal according to the present invention.

FIG. 20B is a sectional view of an instrument inserted into aninstrument seal according to the present invention.

FIG. 21 is a bottom perspective view of an instrument seal and a zeroseal according to the present invention.

FIG. 22 is a bottom perspective view of an instrument seal and a zeroseal according to the present invention.

FIG. 23 is a transparent top perspective view of an instrument seal anda zero seal according to the present invention.

FIG. 24 is a cross-sectional, side view of an instrument seal and a zeroseal according to the present invention.

FIG. 25 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 26 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 27 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 28 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 29 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 30 is a cross-sectional, side view of an instrument seal and a zeroseal according to the present invention.

FIG. 31 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 32 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 33 is a cross-sectional, side view of an instrument insertedthrough an instrument seal and a zero seal according to the presentinvention.

FIG. 34 is a top perspective view of a shield according to the presentinvention.

FIG. 35 is a top perspective, cross-sectional view of a shield insertedin a trocar assembly according to the present invention.

FIG. 36 is a top perspective, cross-sectional view of a shield, a sealassembly and housing according to the present invention.

FIG. 37 is a cross-sectional, side view of a shield, a seal assembly andhousing according to the present invention.

FIG. 38 is a top planar view of a housing and seal assembly according tothe present invention.

FIG. 39 is a cross-sectional, side view of a shield, a seal assembly andhousing according to the present invention.

FIG. 40 is a top perspective, exploded view of a shield and a trocarassembly according to the present invention.

FIG. 41 is a top perspective, cross-sectional view of a shield and atrocar assembly according to the present invention.

FIG. 42 is a top perspective, cross-sectional view of a shield and atrocar assembly according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Turning to FIGS. 1-3, there is shown a surgical access device 10. Onetype of surgical access device 10 is called a trocar 10. A trocar 10provides access to the inside of a patient, such as to the abdominalcavity, during a surgical procedure such as during a laparoscopicprocedure. Laparoscopy is a minimally invasive procedure typicallyperformed through 2-5 small incisions in a patient's abdomen using acamera for visualization. Trocars 10 are placed within each incision andsurgical instruments, along with a camera, are passed through them. Thesurgical access device comprises an elongate tubular structure commonlyreferred to as a cannula 12 that extends along a longitudinal axis froma proximal end 14 to a distal end 16. The cannula 12 has a central lumen13 through which instruments are passed. The central lumen 13, whichextends between openings at the proximal end 14 and the distal end 16,is dimensioned to accommodate a range of instruments, for example,instruments of predetermined diameters and lengths such as scissors,dissectors, graspers and scopes.

The cannula 12 is inserted through a tissue or body wall and into a bodycavity which is pressurized to create an inflated working space for thesurgical procedure. At the proximal end 14, a trocar seal or sealassembly 18 is provided. Located at the top of the cannula 12, the seal18 allows instruments to pass through the cannula 12 while preventingair from escaping from the abdominal cavity. Maintaining proper airpressure is key during a laparoscopic procedure because it allowssurgeons an adequately large working space to properly view the surgicalfield and perform the procedure. The proximal end 14, where the sealassembly 18 is located, has a larger diameter compared to the lower endof the cannula 12, thereby defining a volume in which components of theseal assembly 18 are disposed as best seen in FIGS. 2 and 3. Theenlarged proximal portion defining the seal assembly 18 may beintegrally formed with the narrower distal portion of the trocar 10, oralternatively, the seal assembly 18 may be configured for releasablyconnecting to a distal cannula portion. In either case, the longitudinalaxis and central lumen of the seal assembly 18 is generally coincidentwith the longitudinal axis and central lumen of the cannula 12, andwhich together, define an access channel 13 through the trocar 10. Insome cases, the trocar 10 is provided with an obturator (not shown) thatis inserted into the central lumen 13 and dimensioned to extend past thedistal end of the trocar 10. The obturator has a tissue penetrating tipthat facilitates insertion of the trocar 10 into the patient. Wheninserted into a patient, the obturator is removed and replaced withinstruments for performing the surgical procedure.

The surgical access device 10 is typically manufactured in a range ofsizes to accommodate instruments of different diameters, for example, upto about 5 mm, 8 mm, 11 mm, 12 mm, or 15 mm. Embodiments of the surgicalaccess device 10 have working cannula lengths of about 55 mm, 75 mm, 100mm, or 150 mm. These diameters and lengths are exemplary and a widevariety of sizes may be successfully employed with the presentinvention. The trocar 10 comprises any suitable material, for example, abiocompatible material. In some embodiments, the cannula 12 comprises apolymer, for example, polycarbonate, polyvinyl chloride (PVC),polysulfone, polyamide, polyetheretherketone (PEEK), polyolefin,polyether block amide (PEBAX®), polyepoxide, polyurethane, polyacrylate,polyether, acrylonitrile-butadiene-styrene (ABS), blends, mixtures,copolymers, and the like. In some embodiments, the cannula 12 comprisesmetal, glass, ceramic, and/or fiber. In some embodiments, the cannula 12comprises a composite, for example, comprising reinforcing fibers, areinforcing structure, a layered structure, and the like.

The seal assembly 18 comprises an instrument seal 22, and a zero seal 24located inside a housing 20 and a cap 26 at the proximal end 14. The cap26 engages the proximal end of the housing 20 and has a central opening28 leading into the central lumen 13. The seal housing 20 comprises agenerally hollow cylinder open at both ends and includes a generallycircular step, stop or flange 30 located inside the housing thatprojects circumferentially inwardly from the inner surface of the walltoward the central lumen 13 which contacts one or more of the seals 22,24. The first and second seals 22, 24 are generally connected to thetrocar 10 by being captured between the cap 26 and housing flange 30 aswill be described in greater detail below.

The housing 20 may further include a gas inlet port (not shown)comprising a valve. The gas inlet port fluidly connects the interior ofthe cannula 12 with a source of gas, for example, an insufflation gas,such as carbon dioxide, for delivery into the cannula lumen 13 and intothe surgical site. Some embodiments of the surgical access device 10comprise a housing 20 is separable from the cannula 12.

The seal assembly 18 will now be described in greater detail. The zeroseal 24 prevents gas from escaping the pressurized body cavity throughthe cannula 12 when no surgical instrument is within the working channel13 or central lumen 13. The zero seal or check valve 24 is shown in thefigures as a double-duck-billed seal or valve. The seal 24 has aplurality of cuts and folds configured to create a plurality of flapsthat closing a distal opening of the seal 24. When there is noinstrument inserted through the zero seal, the flaps are closed and nofluid passes across the seal 24. When an instrument is inserted, theinstrument displaces the flaps of the zero seal 24 allowing it to passacross the seal 24. The seal 24 may be any suitable seal such asduck-billed seal or flap seal that completely halts passage of gasacross the seal 24. The instrument seal 22 is located inside the zeroseal 24.

Turning now to FIGS. 4A-4B, a variation of the instrument seal 22according to the present invention is shown. The instrument seal 22 isconfigured to seal against an instrument to prevent gas from escapingthe pressurized body cavity through the cannula 12 when an instrument isinside the working channel 13. When an instrument is extending acrossthe seal assembly 18, the instrument seal 22 is configured to contactthe instrument and to conform around it as much as possible and toremain sealed against it through the many orientations of the instrumentwith respect to the instrument seal 22. The instrument may be displacedinside the central lumen 13 and so the instrument seal 22 must activelyrespond to such displacements and be configured to take a position withrespect to the inserted instrument and seal against it as best aspossible for all of the possible positions of the instrument in order toprevent the escape of gas across the seal 22. The seal 22 includes aninstrument sealing portion or element 32 which may also be called aninstrument engaging portion or member 32. The proximal end of theinstrument engaging portion 32 is connected to a supporting portion ormember 36. And, the proximal end of the supporting portion 36 isconnected to a base portion 38. The supporting portion 36 is, therefore,located between the instrument engaging portion 32 and the base portion38 as shown in the figures.

The instrument engaging portion 32 is enlarged relative to the connectedsupporting portion 36. That is, the instrument engaging portion 32 has alateral dimension measured perpendicular to the longitudinal axis of theseal 22 that is larger than the same lateral dimension taken of thesupporting portion 36. In one variation, this lateral dimension is adiameter; however, the invention is not limited to circularcross-sections of the seal assembly components. The instrument engagingportion 32 may have many operable configurations according to thepresent invention and include the following descriptions. The instrumentengaging portion 32 is bulbous in shape and forms a mushroom-like headconnected to the supporting portion 36. The instrument engaging portion32 is spherical in shape. The instrument engaging portion 32 ishemi-spherical or semi-spherical or spheric or frusto-spherical. Theinstrument engaging portion 32 is a spheric section taken between twoplanes, a first plane and a second plane. The instrument engagingportion 32 is a spheric section taken between two planes, a first planeand a second plane that are perpendicular to the longitudinal axis ofthe seal 22 and parallel to each other. The instrument engaging portion32 is a spheric section taken between two planes, a first plane and asecond plane wherein the first plane is tangential to the sphere. Theinstrument engaging portion is a spheric section taken between twoplanes, a first plane and a second plane wherein the second plane passesthrough the center of the sphere. The instrument engaging portion is aspheric section taken between two planes, a first plane and a secondplane and neither the first plane nor the second plane passes throughthe center of the sphere. The instrument engaging portion is a sphericsection taken between two planes, a first plane and a second planewherein the first plane is tangential to the sphere and the second planepasses through the center of the sphere. The instrument engaging portionis a spheric section taken between two planes, a first plane and asecond plane, and further including a third plane located between thefirst plane and the second plane, the third plane passing through thecenter of the sphere. The instrument engaging portion is a sphericsection taken between two planes, a first plane and a second plane; thespheric section that does not include a third plane that passes throughthe center of the sphere. The supporting characteristics of a sphereadvantageously work to provide optimum transmission of side-to-sideforces while, at the same time, reducing the surface area of material atand/or adjacent to the orifice 34 from contacting an insertedinstrument. In other variations of the instrument engaging portion 32,the word “spherical” and “spheric” used above in this paragraph isreplaced with “ellipsoidal” or “ellipsoid” and hence, the sphericsection may be an ellipsoidal section. Furthermore, the shape of theinstrument engaging portion 32 can be any shape, for example, it can bepolygonal, or geodesic or other shape and/or include one or more flatand/or curved surfaces. The instrument engaging portion 32 is largerthan the supporting portion 36 and forms a dome shape with a distalopening which will be described in greater detail below.

The forward-to-rearward, back-and-forth motion of an inserted instrumentpresents as a drag force or hysteresis where the seal material isalternatively extended and then invaginated or drawn within the sealorifice 34 to a point where it dissociates from a “break-away”characteristic. There is a relationship between the orifice 34 diameterand the overall volume of the hemispherical cavity 35 that maintains apreferred contact angle between the contact edge of the orifice 34(and/or material adjacent to the orifice) and the surface of theinserted instrument. That relationship can best be characterized as acondition wherein the circumferential edge of the orifice 34 issubstantially planar or at nearly a right angle to the axis of aninserted instrument. As such, the overall volume and spherical size ofthe instrument engaging portion 32 and cavity 35 are adjusted tocorrespond to the nominal size of the orifice 34 and, hence, of aninserted instrument. For example, for the insertion of largerinstruments, a larger orifice 34 would be required and hence a largerhemispherical portion cavity 35 to provide the proper minimal contact.

The instrument engaging portion 32 includes an orifice 34 at the distalend of the instrument engaging portion 32. The orifice 34 serves as anexit for an instrument passed into the seal 22. The orifice 34 isdefined by a closed curve on the surface of instrument engaging portion32. The closed curve may be a circle, ellipse, or pseudo circle. Theorifice 34 is sized and configured to correspond to a range of surgicalinstrument shaft diameters and/or shapes. The instrument engagingportion 32 is formed with a wall thickness that provides appropriateelasticity but that slightly restricts inordinate elongation as aninserted instrument is moved from side to side within the workingchannel 13 of the surgical access device 10. A semi-spherical geometryis advantageous because an inserted instrument is not forced intointimate contact with an internal surface as it is directed through theorifice 34 of the seal 22. The semi-spherical geometry advantageouslyprevents the distal-end features of an inserted instrument from damagingthe seal 22 as it is inserted through the orifice 34 off-center. Ashield, which will be described in greater detail below, may be providedto protect the internals surface of the seal 22. The instrument engagingportion 32 is substantially larger in diameter or distance measuredlaterally to the longitudinal axis than the diameter or lateraldimension of the supporting portion 36 to which it is connectedregardless or their shapes. The instrument engaging portion 32 includesan inner surface and an outer surface and a cavity 35. The instrumentengaging portion 32 comprises a resilient structure of sufficientsurface area to allow stretching and folding of the seal material. Theedge of the orifice 34 contacts an inserted instrument. As the insertedinstrument is pushed distally, the inner surface of the instrumentengaging portion 32 may come into contact with the surface of theinstrument. When the inserted instrument is moved proximally, the outersurface of the instrument engaging portion 32 may come into contact withthe surface of the instrument. In either case, whether the instrument ismoved proximally or distally relative to the seal 22, the shape of theinstrument engaging portion 32 minimizes the area of the instrumentengaging portion 32 that comes into contact with the insertedinstrument, thereby, advantageously reducing the friction and dragexerted on the instrument as well as the degree of hysteresis, stictionand oil canning. The instrument engaging portion 32 is configured toprovide the least amount of contact with the instrument in a static ordynamic condition while still providing sealing to prevent the escape ofgas across the seal.

The supporting portion 36 is an elongate tubular structure. Thesupporting portion 36 is cylindrical having an inner surface and anouter surface. The inner surface defines a lumen 42 having a diameter. Awall thickness is defined between the inner surface and the outersurface. The supporting portion 36, at its distal end, is connected tothe instrument engaging portion 32 forming an intersection 40. Theintersection 40, which also can be called a flange, undercut, or lip,extends generally radially outwardly from the supporting portion 36. Thesupporting portion 36, at its proximal end, is connected to the baseportion 38. Together, the supporting portion 36 and the instrumentengaging portion 32 form a mushroom-like shape wherein the instrumentengaging portion 32 defines a head and the supporting portion 36 definesa stem. In one variation, the supporting portion 36 has a wall thicknessthat is greater than the wall thickness of the instrument engagingportion 32 making it relatively more rigid and less flexible. In anothervariation, the supporting portion 36 has a wall thickness that is thesame as the wall thickness of the instrument engaging portion 32. Inanother variation, the supporting portion 36 is rigid or semi-rigidrelative to the instrument engaging portion 32. The supporting portion36 is configured to have the smallest diameter that allows passage of aninserted instrument without undue restriction upon the instrument. Thediameter of the supporting portion 36 is smaller than the diameter ofthe instrument engaging portion 32 and the intersection between the twoportions 32, 36 is defined by a radially expanding portion that may bestraight or curved. The orifice 34 of the instrument engaging portion 32is coaxial with or aligned with the lumen 42 of the supporting portion36. The supporting portion 36 is connected at its proximal end to thebase portion 38.

The base portion 38 extends radially outwardly from supporting portion36 forming a circumferentially extending planar portion that encompassesand extends around the lumen 42 of the supporting portion 36. The baseportion 38 defines the entryway into the lumen 42 of the supportingportion 36 with the lumen 42 being centrally located within theencompassing base portion 38. The base portion 38 includes a proximalsurface 44 and a distal surface 46 defining a wall thicknesstherebetween. The supporting portion 36 connects with the base portion38 at an intersection 48. The base portion 38 is extremely yielding,pliable and flexible. The base portion 38 may further include an annularfeature 50 sized and configured to provide a gas-tight seal between theseal housing 20 and the cap 26. The annular feature 50 extends distallyfrom the distal surface 46 of the base portion 38. The annular feature50 forms a ring of greater thickness.

The instrument and zero seals 22, 24 comprise a suitable elastomericmaterial, for example, rubber, synthetic rubber, silicone, ethylenepropylene diene monomer (EPDM), ethylene-propylene copolymer (EPrubber), polyisoprene, polybutadiene, polyurethane, styrene-butadiene,ethylene vinyl acetate (EVA), polychloroprene (Neoprene®),perfluorelastomer (Kalrez®), thermoplastic elastomer (HYTREL®,PELLETHANE®, KRATON®), as well as blends, mixtures, copolymers, and/orcomposites thereof and the like. They may be made of the same materialor of different materials.

The instrument sealing portion 32, supporting portion 36 and the baseportion 38 may be molded from an elastomeric material as a singlecomponent with each portion having the same thickness. In an alternativevariation, the wall thicknesses of portions 32, 36, 38 are not the same.For example, the instrument engaging portion 32 may have a wallthickness of approximately 0.010 inches, the supporting portion 36 mayhave a wall thickness of approximately 0.020-0.025 inches, the baseportion 38 may have a wall thickness of approximately 0.005 inches andthe annular feature 50 on the base portion 38 may have a wall thicknessof approximately 0.025-0.050 inches. As can be seen from these variousthicknesses, the wall thickness of the base portion 38 is thinner thanthe instrument engaging portion 32 which is thinner than the supportingportion 36. These wall thickness values suggest the principle ofoperation of the instrument seal 22 of the present invention. Inparticular, an instrument is inserted into the working channel 13 andclosely directed to the orifice 34 along the length of the supportingportion 36. Therefore, there may be no need to shield the instrumentseal 22 against the distal end features of an incoming instrument thatmay tear, stretch or impinge upon the inside surface of the instrumentseal 22. Also, once through the orifice 34, the inserted instrumenteasily displaces the orifice 34 because of the relationship between theposition of the orifice 34 and the small-diameter supporting portion 36connected to the resilient base portion 38. The instrument engagingportion 32 together with the supporting portion 36 are substantiallygreater in length than the diameter of the supporting portion 36. Thisarrangement provides a leveraged advantage that allows an insertedinstrument to displace the orifice 34 without elongating the orifice 34.Additionally, the relatively thicker and more rigid support portion 36compared to the instrument engaging portion 32 prevents the instrumentseal 22 from being drawn forward upon insertion of an instrument.

In another variation, the supporting portion 36 of the instrument seal22 is constructed of rigid plastic such as ABS, polycarbonate, PVC orthe like while the instrument engaging portion 32 is made of anelastomer of the like listed above. The supporting member 36 may furtherbe connected to a very resilient base portion 38 constructed of anelastomeric material such as silicone, polyisoprene, polyurethane,Krayton® or the like. The base portion 38 may further include aplurality of bellows or convolutions that enhance material compliance aswill be described below.

Turning now to FIGS. 5 and 6, there is shown a variation of theinstrument seal 22 according to the present invention. In thisvariation, the intersection 48 of the supporting portion 36 with thebase portion 38 is defined by a wall thickness along the supportingportion 36 that is smaller than the remainder of the supporting portion38, thereby, forming an undercut or thin-walled extension 52 of reducedwall thickness. In one variation, the undercut or thin-walled extension52 has the same wall thickness as the base portion 38 as shown in FIGS.5 and 6. The seal 22 of FIGS. 5 and 6 provides a highly flexiblesupporting portion 36. The thin-walled extension 52 is sized andconfigured to allow extreme flexibility from side-to-side, while at thesame time, minimizing longitudinal stretch and deformation. Theproportion or longitudinal length of the undercut or thin-walledextension 52 is determined by the desired side-to-side flexibilitycompared to the tolerable amount of longitudinal deformation. Theremainder of the supporting portion 36 beyond the thin-walled extension52 comprises a wall thickness sized and configured to limit elongation,stretch or longitudinal deformation and transmit the forces moving theorifice 34 from side-to-side to the relatively highly flexible portionscomprising the thin-walled extension 52 and the adjacent base portion 38exclusive of the annular feature 50. The relatively thicker distal endof the supporting portion 36 interconnects with the instrument engagingportion 32 at the intersection 40 in which the wall extends outwardlyand transitions to the instrument engaging portion 32 having a wallthickness that is thinner than the distal end of the supporting portion36 which extends distally to the orifice 34 at the distal end of theseal 22. The wall of the instrument engaging portion 32 is sufficientlythick to prevent inappropriate distortion of the orifice 34 or thesurrounding material and structure so that it can conformingly anduniformly seal against an inserted instrument. Limiting the elongationof the seal 22 to the highly flexible regions that include thethin-walled extension 52 and the adjacent base portion 38 surroundingand interconnected to the thin-walled extension 52 advantageouslyprovides a seal 22 that is stable and does not present inordinatematerial drag or friction upon an instrument inserted into the workingchannel 13. The small linear dimension along the longitudinal axis ofthe thin-walled extension 52 advantageously limits the amount of linearextension of the seal 22 when an instrument exerts forward or rearwardmotion when an inserted instrument moves within the working channel 13.

Turning now to FIGS. 7-10, there is shown a variation of the instrumentseal 22 according to the present invention. The base portion 38 includesat least one convolution, fold, crease, bellow, or the like 54. Theconvolution 54 is formed circumferentially around the working channel 13or lumen 42 of the supporting portion 36 near the proximal opening ofthe supporting portion 36. A single convolution 54 is shown in FIG. 7. Aplurality of concentric convolutions 54 are illustrated in FIGS. 8-10.The convolutions 54 may have smooth curves or sharp angles at each apexof a combination of both. The convolutions 54 add flexibility andextensibility to the base portion 38. The convolutions 54 advantageouslypermit the seal 22 to elongate without stretching the elastomericmaterial which may place undue stress on the material itself or reducethe diameter of the supporting portion 36 if the supporting portion 36were to elongate along the longitudinal axis. The convolutions 54 areuseful in the instance of the seal 22 being sized and configured toaccept both large and small diameter instruments. In addition, theconvoluted geometry is helpful when the material of the seal 22 is of ahigh durometer or stiffness.

Turning now to FIGS. 11-14, there is shown an instrument 56 insertedinto the trocar 10. In particular, the shaft of an instrument 56 isshown in the figures and the proximal end and the distal end are notshown. In FIGS. 11 and 12, the instrument 56 is inserted into theworking channel 13 of the trocar 10 and extends along the longitudinalaxis 58 of the trocar 10. FIGS. 11 and 12 illustrate the instrument 56and the instrument seal 22 in a neutral undeflected configuration. InFIGS. 13-14 the seal housing 20, cannula 12 and zero seal 24 are notshown to illustrate the angulation of the instrument 56 and instrumentseal 22 with respect to the longitudinal axis 58 in a deflectedconfiguration. In the deflected configuration of FIGS. 13-14, thesupporting portion 36 and the instrument 56 are angled with respect tothe longitudinal axis 58. A substantial portion of the base portion 38is not angled and remains substantially perpendicular to thelongitudinal axis 59. Because the seal 22 is connected to the housing 20and retained by a cap 26, at least a portion of the base portion 38remains unmoved and the cap opening 28 remains aligned with the lumen 42of the supporting portion 36 at the proximal end of the seal 22. Theside-to-side motion of an inserted instrument and, hence, theside-to-side displacement of the seal 22 at the proximal end near thecap opening 28 is additionally limited by the proximal opening to thelumen 42 of the supporting portion 36 being in alignment with the capopening 26. Because the cap 26 is rigid, side-to-side displacement ofthe seal 22 at the cap 26 is constrained by the dimensions of the capopening 28. Furthermore, side-to-side displacement of the instrument 56is also limited by the cannula 12 at the distal end of the trocar. Therigid cannula 12 will limit the side-to-side motion of the instrument 56which in turn limits the side-to-side motion of the seal 22 at thedistal end. Because these dimensions are known for a predetermined sizedtrocar 10, the degree or range of pendulation of the seal 22 ispredictable. The present invention in combination with the alignmentallows the use of materials that have here-to-for been less thandesirable because of the coefficients of friction associated with someof them. For example, a soft silicone elastomer may be used in thepresent invention since the amount of material in actual contact withthe surface of the inserted instrument is minimized relative totraditional seals as will be described further below. Other materialsthat have not been optimal for existing designs may, therefore, be usedincluding polyurethane, nylon and polyethylene.

Turning now to FIG. 15, there is shown an instrument 56 inserted into acap 26 and through a traditionally-shaped instrument seal 60. The cavityformed by the instrument seal 60 is substantially large relative to thecavity 35 and lumen 42 of an instrument seal 22 according to the presentinvention as comparatively shown in FIGS. 16-17. In FIGS. 16-17, thetraditionally-shaped instrument seal 60 is shown overlaid with aninstrument seal 22 according to the present invention. Only the cap 26and instrument 56 are additionally depicted to illustrate the comparisonof seals 22, 60. While the footprint at the cap 26 is substantially thesame for both seals 22, 60, the cavity of the traditionally-shapedinstrument seal 60 is quite large compared to the instrument seal 22 ofthe present invention even though the longitudinal length of both seals22, 60 are nearly the same with the instrument seal 22 of the presentinvention being slightly longer. In the present invention, the cavity 35is located distally at the end of the supporting portion 36 of the seal22. The cavity 35 of the present invention is at a location where thetraditionally-shaped instrument seal 22 is tapering in a substantiallyconical fashion to a reduced-sized distal end. In contrast, the cavity35 of the instrument seal 22 of the present invention is relativelyenlarged at the distal end when compared to the traditionally-shapedseal 60. Similarly, the supporting portion 36 of the present inventionis narrower at the proximal end than the proximal end of thetraditionally-shaped seal 60. Furthermore, FIGS. 16-17 clearlyillustrate the conforming supporting portion 26 of the instrument seal22 to the shape and diameter of the inserted instrument 56. Thesupporting portion 26 has a diameter slightly larger than the diameterof an inserted instrument 56. In comparison, the diameter of thetraditionally-shaped seal 60 is much larger along the length of thesupporting portion 36. The substantially equivalent footprint near thecap 26 permits the seal 22 of the present invention to be easilysubstituted for the traditionally-shaped seals 60 without changing thedimensions of the housing 20, seal assembly 18 or trocar 10 itself.

With reference to FIG. 18A, there is shown an instrument seal 22according to the present invention with an instrument 56 inserted intothe working channel 13 of the seal 22 in a normal, static, undeflectedconfiguration. FIG. 18B illustrates another variation of the instrumentseal 22 according to the present invention in which the supportingportion 36 and the base portion 38 are substantially identical to thesupporting portion 36 and base portion 38 of FIG. 18A. In FIG. 18B, theinstrument engaging portion 32 has a different shape. Distal to theintersection 40, the instrument engaging portion 32 of FIG. 18B includesa substantially conical portion 62. In one variation, the outer surfaceis slightly concave as shown. In another variation, the conical portion62 transitions distally to a substantially cylindrical portion 64. Inanother variation, the cylindrical portion 64 is the result of aninserted instrument 56 expanding the orifice 34 such that the innersurface of the instrument engaging portion 32 contacts the outer surfaceof the instrument 56 which is in contrast to FIG. 18A, in which theinner edge of the orifice 34 contacts the outer surface of theinstrument 56. As can be seen in FIGS. 18A and 18B, the contact surface66 of FIG. 18B is greater than in the variation shown in FIG. 18B.

With reference to FIGS. 19A and 19B, there is shown another side-by-sidecomparison of two instrument seals 22 with an inserted instrument 56 ina normal, static, undeflected configuration wherein like referencenumbers are used to describe like parts. FIG. 19A is substantiallysimilar to the embodiments shown and described above in FIGS. 1-18A.FIG. 19B illustrates another variation of the instrument seal 22according to the present invention in which the supporting portion 36and the base portion 38 are substantially identical to the supportingportion 36 and base portion 38 of FIG. 19A. In FIG. 19B, the instrumentengaging portion 32 has a different shape and a different materialthickness compared to FIG. 19A. Distal to the intersection 40, theinstrument engaging portion 32 has a reduced wall thickness compared toFIG. 19A. Also, distal to the substantially spherical (or ellipsoidal)instrument engaging portion 32, the instrument engaging portion 32transitions to a substantially conical or cylindrical portion 64 forminga point of inflection at the point of transition 68 defining a slightlyconcave outer surface. In another variation, the cylindrical portion 64is the result of an inserted instrument 56 expanding the orifice suchthat the inner surface of the instrument engaging portion 32 contactsthe outer surface of the instrument 56 which is in contrast to FIG. 19A,in which the inner edge of the orifice 34 contacts the outer surface ofthe instrument 56. As can be seen in FIGS. 19A and 19B, the contactsurface 66 of FIG. 19B is greater than in the variation shown in FIG.19A which is likely to increase the amount of friction between theinstrument 56 and the seal 22.

Turning now to FIGS. 20A and 20B, there is shown a distal end of theinstrument seal 22 with an instrument 56 inserted into the workingchannel 13 wherein the dotted lines illustrate dynamic or deflectedpositions of the instrument engaging portion 32 relative to its staticor undeflected positions relative to the inserted instrument 56. In FIG.20A, the instrument 56 is in a dynamic distal motion forcing the edge ofthe orifice 34 to be slightly pushed or deflected distally resulting incontact of the orifice edge and possibly a small part of the innersurface of the instrument engaging portion 32 with the distally movinginstrument 56 creating a slight concavity or deflection 70 around theorifice 34. FIG. 20B illustrates the instrument 56 moving proximallyrelative to the seal 22 deflecting or invaginating the instrumentengaging portion 32 at a location near the orifice 34. The inwarddeflection 70 is depicted in dotted lines to contrast the deflected ordynamic position relative to the static or undeflected position of theinstrument engaging portion 32 relative to the seal 22. In the deflectedposition of FIG. 20B, the edge of the orifice 34 and possibly togetherwith a small portion of the outer surface of the seal 22 is in contactwith the translating instrument 56.

The geometry of the enlarged instrument engaging portion 32 provides aseal with reduced frictional drag, hysteresis and stiction when aninserted instrument is engaged with the orifice 34. The generallyhemispherical geometry in combination with the unusual wall thickness ofthe instrument engaging portion 32 provides a direct incentive for theundercut 52 to respond to side-to-side motion of an instrument 56inserted through the distal orifice 34. In addition, it can be seen thatthe small diameter supporting portion 36 in combination with the overalllength of the seal 22 provides a significant leveraged advantage indirecting the seal orifice 34 to respond to the side-to-side motion ofan inserted instrument 56.

Turning now to FIGS. 21-24, there is shown another variation of the sealassembly 18 comprising an instrument seal 22 connected to a zero seal24. The instrument seal 22 is substantially identical to the onedescribed above and includes an instrument engaging portion 32, asupporting portion 36 and base portion 38. The supporting portion 36 isinterconnected between the instrument engaging portion 32 and the baseportion 38. An intersection or undercut 40 is defined between theenlarged bulbous instrument engaging portion 36 and the supportingportion 36 which has a smaller diameter or smaller lateral dimensionrelative to the instrument engaging portion 32. A working channel 13extends from an opening 72 at the proximal end of the seal 22 into thelumen 42 of the supporting portion 36 and into the cavity 35 of theinstrument engaging portion 32 to an orifice 34 at the distal end of theinstrument seal 22. The proximal end of the supporting portion 36 isconnected to the base portion 38 at an intersection 48 which may beprovided with an undercut or thin-walled extension 52 having a reducedwall thickness relative to the distal end of the supporting portion 36.In one variation, the thin-walled extension 52 is the same thickness asthe base portion 38 which includes a relatively thicker annular feature50 for connection to the housing 20 and cap 26. In particular, theannular feature 50 is captured between the cap 26 and housing 20permitting the annular base portion 38 inside the circumference of theannular feature 50 to move such as deflect laterally, translateddistally, and/or stretch in any direction. The instrument seal 22 isconfigured to angulate polyaxially and translate along its longitudinalaxis. The resiliency of the material of the seal permits some stretchrotation about the longitudinal axis.

The zero seal 24 extends between a proximal end 74 and a distal end 76.The zero seal 24 is shown in FIGS. 21-24 as a double-duckbilled seal;however, the zero seal 24 may be of any configuration that does notpermit gas to cross the zero seal 24 when no instrument is inserted. Thedistal end 76 includes an opening 78 that is shown in a closedconfiguration in FIGS. 21-24 and opens by force of an insertedinstrument. The zero seal 24 includes an opening 80 at the proximal end74. The inner surface of the zero seal 24 defines a cavity 82. Theproximal end 74 of the zero seal 24 is connected to the instrument seal22 such that the instrument engaging portion 32 of the instrument seal22 is located inside the cavity 82 of the zero seal 24. The instrumentengaging portion 32 snaps through the opening 80 at the proximal end 74and a circumferential portion of the zero seal 24 seals against theinstrument seal 22. The circumferential portion of the zero seal 24lands proximally of the intersection 40 of the instrument engagingportion 32 and supporting portion 36. The undercut formed by theintersection 40 helps keep the zero seal 24 attached to the instrumentseal 22. The instrument seal 22 may further be provided with acircumferential extension or ridge 83 as shown in FIGS. 8-10, 30-33, and40-42. The ridge 83 extends outwardly from the supporting portion 36.The zero seal 24 is secured to the instrument seal 22 by snappingbetween the radially extending instrument engaging portion 32 and thecircumferential extension 83. In another variation, the instrument seal22 is integrally formed with the zero seal 24. With the zero seal 24connected to the instrument seal 22, the distal opening 78 of the zeroseal 24 is aligned with the orifice 34 and the lumen 42. In thevariation of FIGS. 21-24, the seal assembly 18 is configured such thatthe zero seal 24 is connected directly to the instrument seal 22. Thisconfiguration is different from the variation shown in FIGS. 2-3, 12wherein the proximal ends of both the zero seal 24 and the instrumentseal 24 are connected to the housing 20 by being captured between thecap 26 and the housing 20. With the zero seal 24 connected directly tothe instrument seal 22, the zero seal 24 advantageously translates anddeflects together with instrument seal 22 as shown in FIGS. 25-33. Withthe zero seal 24 connected directly to the instrument seal 22, the zeroseal 24 conforms closely and responds quickly when the instrument isplaced or removed as the zero seal 24 has less distance to assume itsclosed and sealed configuration. The substantially hemispherical shapeof the instrument engaging portion 32 also prevents material drag as theinstrument 56 passes through the seal 22. The thicker wall of thesupporting portion 36 closely approximates the shape of an insertedinstrument such as the cylindrical shape of a shaft of a conventionalsurgical instrument. The supporting portion 36 translates motion to therelatively thinner sections such as the undercut 52 and the base portion38. The proximally located base portion 38 is highly responsive andangulation of the supporting portion 36 simultaneously angulates thezero seal 24 in the same direction.

With particular reference to FIGS. 25-33, the arrangement of the zerovalve 24 attached directly to the instrument valve 22 is especiallyuseful when the seal is configured for use with larger diameterinstruments 56. It can be seen that a small diameter instrument,deployed within a large diameter working channel 13 will not only engagethe orifice 34 but also the opening 78 in the zero valve 24. Instrument56 contacts with both the zero valve 24 and the instrument valve 22associated with the distal portion of the combination. This facilitatesthe transmission of side-to-side movement of a small instrument within alarge channel 13 to the highly responsive base portion 38 and undercut52 and from the instrument seal 22 to the zero seal 24. FIG. 25illustrates a minimum engagement 84 of the instrument engaging portion32 with the smallest instrument 56. The seal and instrument 56 are in astatic undeflected condition. The orifice 34 is sized for the smallestexpected instrument to be inserted providing a minimum engagement 84 ofthe instrument engaging portion 32 to the instrument 56. FIG. 26illustrates the instrument 56 inserted into the working channel 13 andangled to deflect the seals 22, 24. The instrument 56 translates themotion to the base portion 38 angulating the instrument seal 22 at theintersection 48 with the base portion 38. It is noted that in thedeflected configuration shown in FIG. 26, the orifice 34 and the opening78 substantially conform around the instrument 56. Also, because thezero valve 24 is connected to the instrument valve 22, both the orifice34 and the opening 78 in zero seal 24 are in sealing engagement with theinstrument 32 and in alignment with each other. FIG. 27 illustrates theseals 22, 24 angled and conforming to the instrument 56 with theinstrument 56 translated laterally and not angled. FIG. 28 illustratesthe instrument 56 translated even further laterally relative to FIG. 27and the seals 22, 24 are angled even when the instrument 56 is notangled. The seals 22, 24 sealingly engage the instrument 56 in FIG. 28.In traditional seals, this position would result in the seals 22, 24separating away from sealing engagement with the instrument 56. FIG. 29illustrates the instrument not angled and translated in the lateraldirection and the seals 22, 24 are not angled. In this configuration,the orifice 24 lacks engagement 84 on one side of the instrument 56. Inother words, the orifice 34 would “cateye” or elongate and leak. Thisdegree of engagement would result if the instrument seal 22 did not havethe increased flexibility to deflect with respect to the base portion 38and assume a conforming configuration as in FIGS. 27-28. In FIG. 30,there is shown a seal assembly 18 without an instrument 56. FIG. 31illustrates an instrument 56 with a small diameter inserted into theworking channel 13 in a static, undeflected orientation relative to theseal assembly 18. FIG. 32 illustrates a large diameter instrument 56relative to the instrument 56 in FIG. 31 inserted through the sealassembly 18. The seal assembly 18 conforms around the insertedinstrument 56 to seal against it and prevent the escape of gas. FIG. 33illustrates a small diameter instrument 56 inserted into the workingchannel 13 and angled. The instrument seal 22 and the zero seal 24conform about the outer surface of the instrument 56 at the location ofthe orifice 34 and opening 78. FIG. 33 illustrates deflection of theseal assembly 18 in the location of the undercut 52 in the location ofthe intersection 48 of the supporting portion 36 with the base portion38 where the seal wall thickness is reduced. FIG. 33 also illustratesdeformation or stretching of the base portion 38 on the side opposite tothe direction of angulation.

Turning now to FIGS. 34-39, there is shown a shield 86 according to thepresent invention. The shield 86 is a generally tubular, elongatestructure having a proximal end 88 and a distal end 90. The shield 86includes an opening 92 at the proximal end 88 leading into a lumen 96that is interconnected with an opening 94 at the distal end 90. Thelumen 96 of the shield 86 forms at least part of the working channel 13.The shield 86 extends along the length of the instrument seal 22. In onevariation, the shield 86 extends only partly along the longitudinallength of the instrument seal 22. The opening 94 at the distal end 90 ofthe shield 86 is coincident or aligned with the orifice 34 of theinstrument seal 22. Also, the proximal end 88 of the shield 86 and itsopening 92 is aligned with the proximal opening 72 of the instrumentseal 22. The shield 86 is coaxial with the instrument seal 22 and is inclose juxtaposition or in contact with the instrument seal 22 so thatmovement of an inserted instrument is transmitted to the seal assembly.At least part of the distal end 90 of the shield 86 includes a pluralityof slits extending from the distal end 90 toward the proximal end 88forming a plurality of leaflets 98 around the opening 94. In onevariation, the instrument seal 22 is slightly modified to accommodatethe shield 86. In particular, the intersection 48 of the supportingportion 36 with the base portion 38 forms an undercut 52 in theinstrument seal 22 that is located on the inside instead of on theoutside. Hence, the outer surface of the supporting portion 36 appearsto be smooth across the thin-walled extension 52 with the reduction inthe thickness of the wall being seen from inside the instrument seal 22as an undercut 52. The proximal end 88 of the shield 86 includes acircumferential flange 100 that is sized and configured for mating intothe undercut 52 from inside the working channel 13. The shield 86 mayalso be considered a director 86 placed within instrument seal 22 tohelp direct an instrument into the working channel 13. The leaflets 98help direct the instrument toward the orifice 34 of the instrument seal22 as well as protect the material from tearing or interference. Also,the leaftlets 98 make the distal end 90 of the shield 86 more flexibleto unimpede the angulation of an inserted instrument. In FIGS. 34-39,the instrument seal 22 and the zero seal 24 are connected to the housing20.

Turning now to FIGS. 40-42, there is shown the embodiment of the zeroseal 24 connected directly to the instrument seal 22 as described abovewith respect to FIGS. 21-33. The zero seal 24 is shown connected to theinstrument seal 22 by snapping over the instrument engaging portion 32of the instrument seal 22 and being retained between the circumferentialextension 83 and the bulbous instrument engaging portion 32. Thisvariation also includes a shield 86 located within the lumen of theinstrument seal 22 as described above with respect to FIGS. 34-39 andfunctions in the same manner.

It is understood that various modifications may be made to the sealassembly and access device disclosed herein. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the presentdisclosure.

1-18. (canceled)
 19. A surgical access device having a working channelextending along a longitudinal axis between a proximal end and a distalend, the surgical access device, comprising: a seal housing; a cannulaextending distally from the seal housing; a seal assembly disposed inand connected to the seal housing; the seal assembly includes: aninstrument seal having a central lumen extending along a central sealaxis between a proximal opening at a proximal end of the instrument sealand a distal opening at a distal end of the instrument seal; theinstrument seal includes: a base portion at the proximal end of theinstrument seal defining the proximal opening; a cylindrical supportingportion extending distally from the base portion along the seal axis;the supporting portion having a proximal end and a distal end; thesupporting portion includes an inner surface and an outer surfacedefining a constant wall thickness therebetween; the supporting portionhas a circular cross-section taken perpendicular to the seal axis; andan instrument engaging portion extending distally from the supportingportion; the instrument engaging portion is a spheric section takenbetween two planes, a first plane and a second plane; the instrumentengaging portion defines the distal opening at the distal end of theinstrument seal.
 20. The surgical access device of claim 19 wherein thefirst plane and the second plane are perpendicular to the seal axis andparallel to each other.
 21. The surgical access device of claim 19wherein the first plane is tangential to the sphere.
 22. The surgicalaccess device of claim 21 wherein the second plane passes through thecenter of the sphere.
 23. The surgical access device of claim 19 furtherincluding a third plane located between the first plane and the secondplane; the third plane passing through the center of the sphere.
 24. Thesurgical access device of claim 19 further including a third planepassing through the center of the sphere; the spheric section notincluding the third plane.
 25. The surgical access device of claim 19wherein the circumferential edge of the distal opening is substantiallyplanar.
 26. The surgical access device of claim 19 wherein the distalopening corresponds to the size of an inserted instrument.
 27. Asurgical access device having a working channel extending along alongitudinal axis between a proximal end and a distal end, the surgicalaccess device, comprising: a seal housing; a cannula extending distallyfrom the seal housing; a seal assembly disposed in and connected to theseal housing; the seal assembly includes: an instrument seal disposed inthe working channel; the instrument seal having a central lumenextending along a central seal axis between a proximal opening at aproximal end of the instrument seal and a distal opening at a distal endof the instrument seal; the instrument seal includes: a base portion atthe proximal end defining the proximal opening; the base portion extendslaterally outwardly from the proximal opening; an elongate supportingportion extending distally from the base portion along the seal axis;the supporting portion includes an inner surface and an outer surfacedefining a thickness therebetween; the central lumen at the supportingportion defines a first diameter that is constant along the entiresupporting portion; and an instrument engaging portion having a proximalend and a distal end; the instrument engaging portion extending distallyalong the seal axis from the supporting portion; the instrument engagingportion defines the distal opening at the distal end of the instrumentseal; the distal opening having a distal diameter that is smaller thanthe first diameter; wherein the instrument engaging portion andsupporting portion define a mushroom shape.
 28. The surgical accessdevice of claim 27 wherein the instrument seal is allowed to pendulaterelative to the seal housing.
 29. The surgical access device of claim 27further including a zero seal connected to the instrument seal.
 30. Thesurgical access device of claim 29 wherein the zero seal defines adistal opening and the engaging portion is located inside the zero sealproximal to the distal opening of the zero seal.
 31. The surgical accessdevice of claim 27 wherein the mushroom shape has a second diameter thatincreases from the first diameter at the proximal end and decreasesprogressively to the distal diameter.
 32. A surgical access port forpassage through body tissue to provide access to an underlying tissuesite; the surgical access port comprising: a working channel extendingfrom a proximal end to a distal end; the working channel beingdimensioned for receiving a surgical instrument; and a seal assembly forproviding a substantial seal for the insertion of a surgical instrument;the seal assembly being disposed in the working channel and including aseal holder, an instrument seal and a zero seal; the instrument sealincludes a proximal opening formed in a proximal base; the proximal basebeing connected to the seal holder; the proximal base beinginterconnected to a distal instrument engaging portion by an elongatesupporting portion; the elongate supporting portion having a constantinner diameter from a proximal end of the supporting portion to a distalend of the supporting portion; the engaging portion having a distalopening having a diameter smaller than the inner diameter of thesupporting portion.
 33. The surgical access port of claim 32 wherein theengaging portion has an inner diameter larger than the inner diameter ofthe supporting portion.
 34. The surgical access port of claim 32 whereinthe supporting portion closely conforms to an inserted surgicalinstrument and the engaging portion seals against the inserted surgicalinstrument.
 35. The surgical access port of claim 32 wherein theproximal opening and the distal opening of the instrument seal arecoaxial.
 36. The surgical access port of claim 32 wherein the supportingportion has a length between the proximal base and the engaging portionand a ratio of the length of the supporting portion to the diameter ofthe supporting portion of at least 2:1.
 37. The surgical access port ofclaim 32 wherein the engaging portion is bulbous.
 38. The surgicalaccess port of claim 32 wherein the instrument seal pendulates withrespect to the seal holder.